The present invention relates to electrical machines such as (but not limited to) electrical generators and, more particularly, to a manifold of a generator rotor which promotes uniform cooling of the windings of the generator rotor.
In a conventional generator having a rotor and a stator, the rotor is provided with field windings that excite the generator while receiving a current from an excitation current source. The stator is provided with windings from which electrical power is output. Typical rotor construction requires that a field winding be assembled bar by bar, into radial slots milled into a rotor body. Containment of the rotor field windings is typically achieved using rotor wedges, rotor teeth and retaining rings. A carbon filled reinforced enclosure (CFRE) rotor eliminates the need for the coil slots milled in the rotor shaft and enables the assembly of a field winding as a single winding module, one for each pole. It is known to use individual radial manifolds under each coil module with a fixed axial spacing between discharge or ventilation holes in the manifolds.
It is desirable to provide a more uniform cooling to the rotor windings. By providing a more uniform cooling to the rotor windings, “hot spots”(areas of very high temperatures) may be avoided. The advanced physical deterioration of generator components (e.g., insulation) at these areas can thus be avoided, thereby extending the operational life of the generator.